syzbot

=============================
WARNING: suspicious RCU usage
5.15.169-syzkaller #0 Not tainted
-----------------------------
net/sched/sch_api.c:304 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
8 locks held by kworker/1:0/21:
 #0: ffff0000d49e5138 ((wq_completion)wg-crypt-wg0){+.+.}-{0:0}, at: process_one_work+0x66c/0x11b8 kernel/workqueue.c:2283
 #1: ffff80001bcf7c00 ((work_completion)(&peer->transmit_packet_work)){+.+.}-{0:0}, at: process_one_work+0x6ac/0x11b8 kernel/workqueue.c:2285
 #2: ffff0000ce0c8178 (&peer->endpoint_lock){++..}-{2:2}, at: wg_socket_send_skb_to_peer+0x64/0x1a8 drivers/net/wireguard/socket.c:173
 #3: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #4: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #5: ffff800014c82340 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311
 #6: ffff0000cec66908 (&sch->q.lock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #6: ffff0000cec66908 (&sch->q.lock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3875 [inline]
 #6: ffff0000cec66908 (&sch->q.lock){+...}-{2:2}, at: __dev_queue_xmit+0x8a0/0x2ac8 net/core/dev.c:4217
 #7: ffff800014c822e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311

stack backtrace:
CPU: 1 PID: 21 Comm: kworker/1:0 Not tainted 5.15.169-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: wg-crypt-wg0 wg_packet_tx_worker
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 lockdep_rcu_suspicious+0x188/0x1e0 kernel/locking/lockdep.c:6571
 qdisc_lookup+0xc8/0x64c net/sched/sch_api.c:304
 qdisc_tree_reduce_backlog+0x200/0x4e8 net/sched/sch_api.c:800
 pfifo_tail_enqueue+0x280/0x38c net/sched/sch_fifo.c:51
 qdisc_enqueue include/net/sch_generic.h:832 [inline]
 tbf_enqueue+0x2f8/0x5f0 net/sched/sch_tbf.c:237
 dev_qdisc_enqueue+0x60/0x35c net/core/dev.c:3816
 __dev_xmit_skb net/core/dev.c:3900 [inline]
 __dev_queue_xmit+0x1018/0x2ac8 net/core/dev.c:4217
 dev_queue_xmit+0x24/0x34 net/core/dev.c:4285
 neigh_hh_output include/net/neighbour.h:493 [inline]
 neigh_output include/net/neighbour.h:507 [inline]
 ip6_finish_output2+0x132c/0x1cec net/ipv6/ip6_output.c:130
 __ip6_finish_output+0x580/0x6ec net/ipv6/ip6_output.c:201
 ip6_finish_output+0x40/0x218 net/ipv6/ip6_output.c:211
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip6_output+0x274/0x594 net/ipv6/ip6_output.c:234
 dst_output include/net/dst.h:443 [inline]
 ip6_local_out+0x120/0x160 net/ipv6/output_core.c:161
 ip6tunnel_xmit include/net/ip6_tunnel.h:160 [inline]
 udp_tunnel6_xmit_skb+0x43c/0x938 net/ipv6/ip6_udp_tunnel.c:109
 send6+0x560/0x930 drivers/net/wireguard/socket.c:152
 wg_socket_send_skb_to_peer+0xfc/0x1a8 drivers/net/wireguard/socket.c:178
 wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline]
 wg_packet_tx_worker+0x1a8/0x714 drivers/net/wireguard/send.c:276
 process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
 worker_thread+0x910/0x1034 kernel/workqueue.c:2457
 kthread+0x37c/0x45c kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870